Performing at a fan's bat mizvah instead of going to the pre-Grammys press junket and party.
When being given a book of fanart and such from a girl who created a fan project, he said he felt like an asshole for not having anything to give the fan in return.
Throwing a Starship wrap party in Vegas for his Team Starkid friends because he couldn't make it to every single performance of the show.
Darren giving his friend Brian Holden, of Starkid fame, a hug during Darren's performance of "Silly Love Songs", in Chicago, for Glee Live!
Pretty much anytime Darren performs and one of the Starkids are there, he'll acknowledge them or ask them to perform a song with him. Joey Richter, Lauren Lopez, Dylan Saunders, and Joe Walker have all performed their signature AVPM songs with Darren.
Darren + Starkids = Heartwarmness again, this time at Leaky Con, at the end of "Home" specially, where they all hugged him.
Definitely this performance of "Teenage Dream". If you were a fan before he became famous it's also a HUGE Tear Jerker.
Upon meeting Kellen Sarmiento the mini-Warbler, Darren went over to give him a hug. The fan screaming got even louder during those eleven seconds.